Platform Bridge
The layer that puts your brand inside Apple's and Google's own design systems. 112 variables on two modes: Brand resolves a platform role to an Appetite token, System returns the platform's published value. One dropdown moves a whole screen.
What it covers
Appetite UI does not replace the Apple and Material design systems. It names their slots and points each one at a token you control. 112 slots, 52 from Apple and 60 from Material, covering colour, shape and type size. Nothing here redraws a component. It decides where a component reads its value from.
A second collection, Platform, is easy to confuse with this one and does a different job. It holds 16 variables on three modes, ios-md, ios-lg and android, and it carries geometry rather than colour: min-touch-target 44, 44, 48; bar/top-height 44, 44, 64; control/corner 8, 8, 9999. The two iOS modes differ in exactly one variable, grid/safe-area/top at 59 and 62.
Brand mode
In Brand mode a platform slot stops being a colour and becomes a pointer. iOS/tintColor points at brand/base, which points at colors/blue/500, and that primitive is the only place the hex is written down. M3/sys/color/primary ends on the same primitive, so one edit moves an iOS screen and an Android screen together.
Two platforms, one brand colour, one source. Both accents end on colors/blue/500.
101 of the 112 slots resolve to an Appetite token in Brand mode. The other 11 hold a platform value or a bare number in both modes, and they are named under What does not move.
System mode
Switch the collection to System and every slot drops its pointer and returns the value Apple and Google publish. Nothing is approximated. Those values sit in Color Tokens as 67 untouched platform primitives, stored once and never retyped into a component. It is one switch on the frame, not a rebuild. The screen stops being yours and becomes theirs, which is what a native review asks to see.
A few slots land on the same value in both modes without being wired that way. The Appetite grey scale and Apple's systemGray already agree at #8E8E93.
Typography
The Bridge carries type, not only colour. 11 iOS text styles and 15 Material typescale steps each point at an Appetite step in Brand mode and return the platform's own published size in System mode. It carries the size step only, not weight, line height or letter spacing.
The Appetite scale is coarser than either platform ramp, so steps collapse in Brand mode. iOS headline and body both land on fontSize/lg, and footnote, caption1 and caption2 all land on fontSize/xs. Distinctions Apple draws a point apart do not survive the switch.
What does not move
Fourteen slots are wired to the same source in both modes. Eleven are the ones counted out of the 112 under Brand mode, and the switch cannot reach them. Three run the other way: they take an Appetite token like the other 101, then keep it.
Keeping the Appetite token in those three is the honest result, not a gap.